Treating leather-impregnating material



f like are particularly referred to.

It was proposed in British Patent 1962 of Patented Feb. '4, 1930 STATESSWAMPSCOTT, MASSACHUSETTS, A SSIGNOR TO VAN T-KSBEL SOI E'& LEATHER.CORPORATION, OF NORWICH, CONNECTICUT, A. CORPORA- TH JN OI" MAINE i V V-'TBE ATING LEATHER-IMPREGNAT INC MATERIAL Rom-swing. Application filedJune 12,

.The present invention relates to an improvment inwate'r-proofingleather, particularly leather tanned with chromium compounds (eitheralone or inconjunction with vegetable tanning agents), by the employmentof molten mixtures includmg paraflin .Wax and a rubber-likewater-insoluble gummy materialJAs examples of the latter classotmaterials, raw rubber, waste rubber (vulcanized or not), gutta-perchaand the 1865, toiemploy a mixture of rubber or gutta, percha and beeswaxor paraflin wax, for imprgnating leather, and inaccordance with thedescription of suchprocess, the twomaterials, namely the gum and thewax" were melted together at a temperature of 220 F. up to 240 F. or inany event at temperatures 2 not above 260 F., and so far as I have beenadvised, the process never came into commer:

cial use, and'experiments have shown that with such mixtures, heatedeven to such mazfilnmn temperature statedin, said patent, viz

260 F. (127 0.) thevi-scosity of the K112iture is so high, attemperatures of 90 to 95 0., that the mixtur'e'will not readilypenetrate tov any substantial extent into leather.

' -More recently it was proposed to employ parafiin wax and rubber,heated to tempera tures of about 150; 0., under which conditions it wasfound that the viscosity of the mixture, at the temperature at which therubber-paraflin mixture was to be brought into contact with the leather,was lowered to such an extent as to permeate the leather to a sufilcient extent. I have now found that itis possible to'still furtherreducethe viscosity, and to accord ingly increase the capacity of the mixturefor impregnating leather,bysuitable mechanical treatments of suchmixture. The mechanical treatment which hasgiven most satisfactoryresults in practice is to pass the said mixture, while in a moltenstate, through a colloid mill. Other treatments such as passingthe saidmixture, while molten, through a homogenizer under high pressure, andeven heating to temperatures of 150 0. or higher for a protracted,period also are capable of 1926. serial no. 115,682.

As illustrating the effect of heat upon the viscosity, it is stated thatwith a mixture of paraflin wax and 15% rubber, which has been heatedonly to 127 0., the viscosity (measured on a Scott viscosimeter) wasabout "7000 seconds, whereas with the same mixture after heating toabout 150 0., the viscosity had dropped to'about 480 seconds. It will beunderstood that the viscosities, as referred to herein, are measured bythe number of seconds required for a given volume (50 c. c.)

of the moltenmaterialat a stated temperature, to flow out through asmall tube, so that a high number represents a high viscosity.

Samples of the above mixture, made up in the proportions. of 85%paraflin wax to 15% rubber, were passed through colloid mills, at .atemperature of 150 0., with the following results Colloid mill treatmentat 150 0'.

15,inch' mill .010 inch clearance Viscosity 387 seconds 15 inch mill.002 inch clearanceuviscosity 340 seconds 10 inch mill .002 inchclearance viscosity'337 seconds 10 inch mil1 .010 inch clearanceViscosity 425 seconds The above figures compare with the viscosity of480 seconds of the same material not a varied, and the resultingviscosity will be approximately in proportion to the percentage ofrubber in the mixture.

-. F or the purpose of comparison, all of the viscosities referred to inthe present case were measured at 0., which 15 about the temperaturepreferably used in impregnating the leather, although this impregnationoperation can be carried on at term eratures a little higher than this,but preferably temperatures of over 100 0. are notemployed in theimpregnation operation. It will be understood that any of thesematerials at 0. have a slightly lower viscosity than at90 0.

It will be understood that proportions of rubber considerably above 15%can be employed, for exampleI may employ mixtures containing 'to or evenmore of rubber, which are particularly useful w th thin leather such asis used for making shoe uppers.

It will be understood that the impregna tion can be partial or complete,and even a- 7 ing the mixture through the colloid mill or through thehomogenizer at a temperature of about 150 (1., it will be understoodthat temperatures somewhat higher than this can be employed, althoughobviously temperatures which would injure the rubber chemically shouldbe avoided. Temperatures somewhat lower than 150 (3., likewise can beemployed, with some improvementof the penetrating qualities of themixture.

I have above referred to mixtures consisting of paraffin Wax and rubberonly; It will be understood that the addition of resins, other gums,waxes, fats,.drying or non-drying oils, coloring matters and the like isnot precluded. Theamonnts of the latter if added,

should preferably not be such as to greatly modify the physicalconsistency of the material whichshould, at normal :room temperature bea relatively firm waxy solid, and not a guildpr paste or jelly or thingreasy mass.

1. A process of treating a mixture including parafiin wax and awater-insoluble rubbery gum, which comprises subjecting such mixture,while in a molten state, to a mechanical treatment capable of loweringthe Viscosity thereof and capable of increasing the permeability thereofto a degree greater than would be eflected by once heating the mixtureof the rubber.

to 150 (1., all without heating sufliciently to substantially injure theproperties of the rubber.

2. A process of treating a mixture including paraffin wax and awater-insoluble rubbery gum, which comprises passing such mixturethrough an extremely fine o ening, while in a molten state, all w thouteating sufliciently to substantially injure the properties 3. A processof treating a mixture including paraflin wax and a water-insoluble'rubbery-gum, which comprises passing such mixwhile molten, through acolloid mill.

at 95 (1, correspondin ture while mt flowable state through an extremelyfine opening, while under substantial superatmospheric' pressure, allwithout heating sufliciently to substantially injure the propertiesofthe rubber. a

4. A process which comprises subjecting to a homogenization treatmentunder substantial superatmospheric pressure, a molten mixture comprisingparaflin wax and a rubberlike gum, all without heating sufliciently toiubstantially injure the properties of the rub- ,5. -A process whichcomprises passing a molten mixture containing parafiin wax and aWater-insoluble rubber-like gum, through a colloid mill.

, 6. A process which comprises passing a molten mixture containingparaflin wax and a Water-insoluble rubber-like gum, through a colloidmill while at about 150 C.

7. A process which comprises subjecting a molten mixture containing arubber-like water-insoluble gum and paraffin wax, to violent mechanicalagitation while passing the same through a fine opening.

8. In the impregnation of leathery material, with a molten mixturecontaining paraflin wax and a rubber like gum, the preliminary treatmentof such' mixture by passing,

9. In the impregnation of leathery material with a molten mixturecontaining paraflin wax and a rubber-like gum, the preliminary treatmentof such mixture by passing same, while molten, through extremely fineopenings.

10. A mixture of the character described suitable for impregnatingleather, containing paratfin wax and a water-insoluble rubher-like gum,the viscosity of such mixture above 340 seconds, based said rubber-likegum.

on a 15% content of or to not substantially 11. A mixtureof thecharacter described I suitable for impregnating leather containingparaflin wax and a water-insoluble rubberlike gum, the viscosity of suchmixture at 95 C., corresponding to substantially below 480 seconds;

12. A mixture containing parafi in wax and a rubber-like gum which whenmolten has a low viscosity such as would result from mechanicalattrition, such viscosity being substantially lower than that whichwould result from merelyheating the mixture once to 150 C;

13. A rubber and paraflin mixture containing about 15% of rubber, andhaving a viscosity at 90 0., substantially below 480 seconds (Story).

14. A rubber and paraflin mixture containing about 15% of rubber, andhaving a viscosity at 90 0., notsubstantially above 425 seconds (Story).

15. A rubber and parafiin mixture in which ,7 W lls. viscosity.

I the paraflin is the ma'or constituent, having a viscosity suflicientlyow to readily permeate sole leather to the center, and havin a viscositlower than would be imparted y once heating to 150 0., and free fromsuch decom sition pro need by satin?l same to 275 C.

16. A process w ich comprises mechanically wearin down a mixture'of arubberlike gum an paraflin, sufiiciently to reduce 17. A process whichcom rises subjecting a hot mixture of a rubber-1i e gum and par aflinwax, to attrition sufliciently to lower its viscosity.

In testimon whereof I aflix 111 Si ature.

EDWA D D. VAN TA SE JR.

roducts of rubber as would be

